For-Met-Phe-OH: Properties, Applications & Sourcing Guide

For-Met-Phe-OH is a synthetic N-formylated dipeptide consisting of formyl-methionine and phenylalanine that serves as a biochemical tool for studying N-formyl peptide receptor (FPR) signaling and innate immune cell chemotaxis in research settings.

Full Chemical Name

N-Formyl-L-methionyl-L-phenylalanine

SKU

N1029684

Peptide Class

N-Formyl dipeptide

Biological Target

N-Formyl Peptide Receptors (FPR1/FPR2)

Primary Research Use

Chemotaxis assays, innate immune signaling studies

Terminus Modifications

N-terminal formyl group; C-terminal free acid (OH)

Chemical Structure and Nomenclature

For-Met-Phe-OH, formally named N-formyl-L-methionyl-L-phenylalanine, is a dipeptide in which the alpha-amino group of methionine carries a formyl (–CHO) protecting group and the C-terminus terminates as a free carboxylic acid. The abbreviation follows standard peptide notation: For denotes the N-formyl cap, Met and Phe are the one-letter–equivalent three-letter amino acid codes, and OH specifies the unprotected C-terminal acid rather than an amide.

This structural motif mimics the N-formylmethionine (fMet) start codon translation product found at the N-terminus of prokaryotic and mitochondrial proteins. Because mammalian cytoplasmic ribosomes do not incorporate fMet, the immune system exploits formylated peptides as pathogen- and damage-associated molecular patterns (PAMPs/DAMPs), making For-Met-Phe-OH a relevant pharmacological probe.

Mechanism of Action: FPR Receptor Engagement

For-Met-Phe-OH acts primarily through N-formyl peptide receptors, a family of G-protein-coupled receptors (GPCRs) that includes FPR1 and FPR2. Upon binding, these receptors activate pertussis-toxin-sensitive Gi proteins, leading to downstream events such as phospholipase C activation, intracellular calcium mobilization, and activation of the NADPH oxidase complex responsible for the respiratory burst in phagocytes.

The two-residue formyl peptide For-Met-Phe is shorter than the classical three-residue probe fMLF (N-formyl-methionyl-leucyl-phenylalanine) and may therefore exhibit distinct receptor selectivity or potency profiles. Researchers use such structural variants to map ligand–receptor structure–activity relationships (SAR) within the FPR family and to dissect the contributions of individual residues to receptor activation.

Key cellular responses triggered downstream of FPR activation include directed migration (chemotaxis), superoxide anion production, degranulation, and cytokine release—all processes central to neutrophil-mediated innate immunity.

Research Applications

Chemotaxis assays: For-Met-Phe-OH can be used as a chemoattractant gradient to recruit neutrophils, monocytes, or transfected cell lines expressing FPR1/FPR2 in Boyden chamber or microfluidic migration assays, providing a shorter formyl peptide control relative to fMLF.

Receptor pharmacology and SAR studies: The compound serves as a structural probe to investigate the minimum peptide length required for FPR activation and to benchmark novel FPR ligands. Competitive binding assays using radiolabeled or fluorescent fMLF analogs can quantify For-Met-Phe-OH affinity.

Innate immunity and inflammation models: In vitro and ex vivo studies of neutrophil activation, reactive oxygen species (ROS) production, and degranulation can employ For-Met-Phe-OH to stimulate or prime phagocytes, contributing to mechanistic understanding of sterile inflammation triggered by mitochondrial damage.

Mitochondrial DAMP research: Because mitochondria retain prokaryotic protein synthesis machinery, their released formyl peptides are recognized by FPRs. For-Met-Phe-OH mimics such mitochondrial signals, making it useful in models of tissue injury and sterile inflammation.

Handling, Storage and Quality Considerations

Solubility: N-formyl dipeptides are typically soluble in polar organic solvents such as dimethyl sulfoxide (DMSO) or dimethylformamide (DMF). Stock solutions are commonly prepared at 10–100 mM in DMSO and then diluted into aqueous buffers immediately before use to minimize hydrolysis. Verify solubility empirically for each lot.

Storage: As with most synthetic peptides, For-Met-Phe-OH should be stored desiccated at –20 °C or below, protected from light and moisture. Avoid repeated freeze-thaw cycles; aliquot stock solutions upon first use.

Purity and characterization: Aladdin Scientific reagents are characterized to confirm identity and purity. Researchers are encouraged to request a Certificate of Analysis (CoA) for lot-specific data including HPLC purity and mass spectrometric confirmation of molecular weight.

Safety: Handle in accordance with standard laboratory safety guidelines. As a peptide reagent, For-Met-Phe-OH is not classified as a highly hazardous material under routine conditions; however, consult the Safety Data Sheet (SDS) before use and wear appropriate PPE.

Frequently asked questions

What is the difference between For-Met-Phe-OH and the classic chemoattractant fMLF?

fMLF (N-formyl-Met-Leu-Phe) is a tripeptide widely used as a high-potency FPR1 agonist, whereas For-Met-Phe-OH is a dipeptide lacking the central leucine residue. This structural difference may result in lower receptor binding affinity or altered selectivity between FPR subtypes. For-Met-Phe-OH is therefore useful as a SAR probe to understand the contribution of peptide length to FPR activation.

In which cell types is For-Met-Phe-OH most commonly used?

For-Met-Phe-OH is primarily used with cells that express N-formyl peptide receptors, most notably human or murine neutrophils, monocytes, macrophages, and dendritic cells. It is also employed with FPR-transfected heterologous cell lines (e.g., HEK293 or CHO cells) to study receptor pharmacology in isolation from confounding endogenous responses.

How should I prepare a working solution of For-Met-Phe-OH for cell-based assays?

Dissolve For-Met-Phe-OH in anhydrous DMSO to make a concentrated stock solution (e.g., 10–50 mM), then aliquot and store at –20 °C. For each experiment, thaw one aliquot and dilute with warm, serum-free assay buffer to the desired working concentration, keeping the final DMSO content below 0.1% to avoid cytotoxicity. Prepare fresh dilutions on the day of the experiment.

Is For-Met-Phe-OH suitable for in vivo studies?

While formyl peptides including longer analogs such as fMLF have been used in animal models of inflammation (e.g., peritoneal recruitment assays), the suitability of For-Met-Phe-OH specifically for in vivo use depends on its stability, potency, and the experimental model. Researchers planning in vivo work should validate the compound's activity in their system and consult the current literature and institutional guidelines for dosing and administration routes.

References

1. Schiffmann E, Showell HV, Corcoran BA, Ward PA, Smith E, Becker EL. The isolation and partial characterization of neutrophil chemotactic factors from Escherichia coli. J Immunol. 1975;114(6):1831-1837.
2. Boulay F, Tardif M, Brouchon L, Vignais P. The human N-formylpeptide receptor. Characterization of two cDNA isolates and evidence for a new subfamily of G-protein-coupled receptors. Biochemistry. 1990;29(50):11123-11133.
3. Zhang Q, Raoof M, Chen Y, et al. Circulating mitochondrial DAMPs cause inflammatory responses to injury. Nature. 2010;464(7285):104-107. doi:10.1038/nature08780
4. Ye RD, Boulay F, Wang JM, et al. International Union of Basic and Clinical Pharmacology. LXXIII. Nomenclature for the formyl peptide receptor (FPR) family. Pharmacol Rev. 2009;61(2):119-161. doi:10.1124/pr.109.001578

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